Studies on the Antigenicity of Bacterial Polysaccharides Part 5: On the Streptococcus Polysaccharide

With the use of pepsin the author has extracted a polysaccharide by digesting Streptococcus viridans. Having carried out precipitation between this polysaccharide and anti-streptococcal rabbit serum, the following results have been obtained. 1) From 1.3 gm of wet bacilli of Streptococcus viridans 43.75 mg. of polysaccharide has been obtained, which is found to be soluble in physiological salt solution. 2) In the precipitation reactions titers are; antigen titer, 1:10,000 by Uhlenhuth method; and antigen titer, 1:10,000, antibody titer 1:250 and antigen titer of binding zone 1:2,500 by antigen-antibody-dilution method. Furthermore, Antigen titer has been found to be 1:10,000 in antibody-dilution 1:50 and antibody titer 1:250 and antigen titer of binding zone 1:2,500 by mixprobe method. 3) In the agglutination of bacillus, owing to the difficulty in getting uniform bacillus emulsions of streptococcus, it has been found quite difficult to determine definitely the agglutination. 4) A long storage of this polysaccharide is also possible.